In m0n0wall 1.8.1, the base system has been switched to FreeBSD 8.4 for better support of recent hardware.
Thanks to contributions by Andrew White, Lennart Grahl and Pierre Nast, there have been significant improvements, new features and bug fixes in many areas.

Please note:

This version requires at least 128 MB RAM and a disk/CF size of 32 MB or more

major overhaul of wireless LAN support. On some cards, it is now also
possible to create multiple APs at the same time. To reflect this
change, the wireless settings have moved to the Interfaces: assign
page, where WLAN subinterfaces can be created much like for VLANs.

Make rule moving and deletion on shaper rules page work like for firewall rules.

Initial support for USB modems

enable CPU hardware crypto support

automatically reassign available physical network interfaces if none
of the assigned interfaces in the configuration can be found on the system
(i.e. for a new installation, or when moving an existing config to new
hardware)

the "embedded" image is gone; generic-pc-serial should now be used for PC Engines and Soekris boards